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	hartrees
Energy at 0K	-154.710171
Energy at 298.15K	-154.713200
HF Energy	-154.710171
Nuclear repulsion energy	98.764770

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3237	3128	0.00
2	A_g	1630	1575	0.00
3	A_g	1112	1075	0.00
4	A_g	954	922	0.00
5	A_u	869	840	0.00
6	A_u	541	523	0.00
7	B_1g	858	829	0.00
8	B_1u	3226	3117	33.93
9	B_1u	1637	1582	3.66
10	B_1u	1057	1021	0.36
11	B_2g	584	565	0.00
12	B_2u	3205	3097	22.94
13	B_2u	1263	1220	39.42
14	B_2u	702	678	9.03
15	B_3g	3189	3081	0.00
16	B_3g	1183	1143	0.00
17	B_3g	854	825	0.00
18	B_3u	576	557	143.37

Atom	y (Å)	z (Å)
C1	0.666	0.789
C2	0.666	-0.789
C3	-0.666	0.789
C4	-0.666	-0.789
H5	1.433	1.553
H6	1.433	-1.553
H7	-1.433	1.553
H8	-1.433	-1.553

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5787	1.3316	2.0653	1.0825	2.4647	2.2336	3.1451
C2	1.5787		2.0653	1.3316	2.4647	1.0825	3.1451	2.2336
C3	1.3316	2.0653		1.5787	2.2336	3.1451	1.0825	2.4647
C4	2.0653	1.3316	1.5787		3.1451	2.2336	2.4647	1.0825
H5	1.0825	2.4647	2.2336	3.1451		3.1056	2.8666	4.2263
H6	2.4647	1.0825	3.1451	2.2336	3.1056		4.2263	2.8666
H7	2.2336	3.1451	1.0825	2.4647	2.8666	4.2263		3.1056
H8	3.1451	2.2336	2.4647	1.0825	4.2263	2.8666	3.1056

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.849
C1	C3	C4	90.000	C1	C3	H7	135.151
C2	C1	C3	90.000	C2	C1	H5	134.849
C2	C4	C3	90.000	C3	C1	H5	135.151
C4	C2	H6	135.151	C4	C3	H7	134.849

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3LYP/6-311G*

States and conformations

	Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Number	Element	Mulliken
1	C	-0.193
2	C	-0.193
3	C	-0.193
4	C	-0.193
5	H	0.193
6	H	0.193
7	H	0.193
8	H	0.193

<r²>	57.959
(<r²>)^1/2	7.613

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3LYP/6-311G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)